Walter Sydney Masterman (1876 - 1946) was an English author of mystery, fantasy, horror and science fiction novels and stories.
The Leather Case is an adventure story about a young man who has just reached Paris after five years working in India as an engineer. While in Paris, he is startled by seeing a young woman whose face seems remarkably familiar, although it is impossible that he can have ever met her before. Moreover, the companion of the girl - apparently an uncle - seems to be going out of his way to engage the young engineer in a mysterious project in Silesia.
Eventually the young man remembers an incident in the trenches during the great war when he saved an enemy officer who was bleeding to death. The Prussian officer had given him a leather case containing two photographs - and one of them is a dead ringer for the mystery woman in Paris. But who are these people that are now trying to entice him to a remote part of Silesia - and what can they really want with him?